Control valve



H. KIRKHAM CONTROL VALVE sept. 2, 1952 Filed Aug. 27, 1947 2 SHEETS-' SHEET 1 A TTOENEYJ H. KIR KH AM CONTROL VALVE Sept. 2, 1952 2' SHEETS-SHEET -2 Filed Aug. 27, 1947 .IN V EN TOR. HAU K/EKHAM J ZM ATTO NEYS l/zfl/lllz//zl f/f .l v//ll/f////////////// Patented Sept. 2, 1952 UNITED STATES CONTROL VALVE Hall Kirkham, Cleveland Heights, Ohio, assignor, by mesne assignments, to The New York Air Brake Company, New York, N. Y., a corporation of New Jersey Application August 27, 1947,'Serial No. 770,882-

This invention relates to hydraulic systems employing double-acting power cylinders and is particul'arly vdirec-ted to improving the control of such cylinders. In its preferred form the invention -is embodied in Ian improved control valve for hydraulic systems such as are used, for example, tocontrol the position of the earth moving blade of -a bulldozer.

For this purpose the double-acting cylinder is coupled to the bla-de, and is incorporated in a fluid system including also a reservoir, a pump, and a control valve. The control valve is manually settable` to cause the cylinder to operate in any one of iour'wayst' lin the rai-se position of the valve the blade is elevated; in the lower position the blade is forced downward; in the hold position the blade is locked against movement; and in the float posi-tion ofthe valve the blade is left free to move up or down under the action of extern-al forces.

This particular application of the improved control system will be explained herein. However, similar control phases are utilized in many applications of power cylinders, and the system of the invention is of general utility lapart from bulldozers, hoists, and the like.

In the operation of double--actingvhydraulic devices, conditions arise, dependent upon connected mechanical apparatus, necessitating extremely accurate control of the position of the ram piston, with means to 'prevent movement of the piston out of control of the operating liquid, as, for instance, under the eifect of the external load. In the use of a bulldozer for grading,

for example, it isimportant'that the blade be raised, held, lowered, or permitted to float under the instant and accurate control of the operator. Diiiiculties have heretofore been experienced in equipment of this sort when attempts were made to lower the blade by placing the valve in Ithe lowering position, or, as Vis. often done, by placing the valve in the float position. The great weight of the blade tends to withdraw the ram piston from the liquid kfollowing it and intended to regulate the rate of lowering on release of the liquid supporting the piston". The resulting erratic operation prevents the-precise control of the blade necessary to accurate. grading.

One factor contributing to the diiiculty of control is the fact that in many installations the rate of delivery .cf the pump is variable, the pump usually being driven from the engine which provides motive power for the tractor. Thus, a system which might be entirely adequate under constant fluid delivery conditions may prove unsatisfactory when -applied to a bulldozer.

If the external-load forces thepiston ahead of the supply of fluid behind it, creating a vacuum, control of the blade .is lost until the pump has lled the cylinder. The present invention, by

14 Claims. (Cl. Gil- 52) preventing such conditions,- assures immediate response of the blade to its control-,in all situations.

The present invention is directed to securing a number of improvements in double-acting hydraulic systems, which may be briefly summarized asfollows:` l

Smooth control of vthe power cylinder under all conditions of operation, and with widely varying rates of delivery of oil from the pump;

Elimination of Verratic or jerky action of the power cylinder; l

Control of"A the return ilow from the cylinder to the reservoir in all phases of cylinder operation;

Maintenance of positivepressure on both faces of the piston .at alltimes; l

Immediate response of the cylinder to raise or "low-er settings following cylinder movement in iioatsettlng; Y

Elimination of flutter in the valve; and Ada'ptability to tandem operation of valves. These results are attained by the user of a new combination of elements in a hydraulic power system which cooperate in a novelway in the control of the system, as will be apparent from the description herein of a preferred embodiment of the invention. This new combination of parts includes one or more of the following subcomisinati-ons:

A manually settable valve and a flow control valve, the former being constructed to direct the flow from the pump and cylinder through the latter in all positions except fHold;

' Means for damping ofthe movement ofthe iow control valve, primarily the openingmovements, thus preventing valve overtravel;

Provision for actua-tion of the flow control valve by relatively small hydraulic and elastic forces, and provision of a lightweight valve;A

'A flow control valve with a set of'ports', graduated in size and staggered in position, to provide more sensitive control of small flow;

VAn exit chamber for the valve so constructed that it may -readily'be converted into twochambers, one for returnA of oil from a relief valve, and one for diversion of oil -toa second control device.

Although, in its preferred form, the invention embodies all the characteristics and advantages stated above, it will be apparent to those skilled in the `art that, in certainapplications, certain of the parts and subcombinationsmay be omitted in the event that the installation is such as not to require them; v

The invention maybe better understood by reference to the drawings which accompany ,this specification and in which: f 1

Fig. l is a longitudinallsection of a control valve f -in accordance with the' invention; and f Figs. 2 to 5 are diagrams of a hydraulic system incorporating the said valve, illustrating different phases of operation thereof, with the valve shown somewhat schematically.

General description of the system Before proceeding to the detailed description of the valve, which is essential to the understanding of the invention, -a typical hydraulic power system incorporating the invention will be described generally with reference to Figs. 2 to 5. It should be understood that the valve is shown schematically in these figures. A suitable fluid, usually a light oil, is contained in a tank (Fig. 2) from which it is continuously fed by the pump 6 into the inlet port 8 of the valve 9. The valve selectively controls the inflow and .out'ovv of iluid through its ports VII yand I2 to the double-acting cylinder I5 in which the pis-ton I6 is reciproci-able. The valve also controls `the return of fluid to the tank from its ports I3 and If4. The operation of the cylinder is controlled manually by setting a plunger 2l to any one of four positions.

In the hold position of Ithe valve illustrated in Fig. 2, outlet ports II and I2 are closed, locking the fluid in both ends of the cylinder, and -f the pump discharge is returned to the tank through the port I4. In the raise position illustrated in Fig. V3, where Work requiring hydraulic pressure is being done, fluid is circulated through the valve .and out of port II into the left A end of the cylinder. Fluid displaced from the right end of the cylinder passes through port I 2, an automatic flow control. valve 32 in the valve 9, and from the port I3 to the tank. In the lower position (Fig. 4), the operation is similar to that in raise except that port I2 is connected to the pump and port I I through the flow control valve to the port I3. In the float position (Fig. 5), the two ends of the cylinder .are coupled together and coupled to the pump, and are also coupled to the return port I3 through the flow control valve 32. The piston is thus free to move in the cylinder.

Valve construction Considering now the preferred form of the valve in detail as shown in Fig. l, the valve body or casing 22, which may be cast, is formed for mounting immediately beneath Ithe tank 5, which may be secured to the valve in any conventional manner, a gasket 85 sealing the junction of the tank and valve. The return ports I3 and I4 open directly in register with correspon-ding apertures in the bottom of the tank 5.

A through bore 23 in the 'casing forms a cylinder for reciprocation of the valve operating plunger 2I, which is dimensioned for a close lit therein.

The left end of the bore 23 is counterbored to receive a seal assembly 24, and the right end is similarly counterbored to receive a detent housing 25 fitted with a seal 26 and retained by screws` 2'I. The outer surf-ace of th-e plunger 2I is formed with four lands 55, 56, 5l, and 58 separated by three sections of reduced diameter 58, 68, and BI. The valve is illustrated in the hold position, in which the reduced portions 59 and E0 of the valve plunger register with internal passages 48 and 49, respectively, which communicate with the external discharge ports II and I2, which, as previously described, are coupled to the operating cylinder I5. i v j In this position, the portion 6I registers with a branch 44h of the inlet chamber 44 into which the pump discharges through port 8, and with'a chamber 45a. The plunger 2-I is bored out to form passages 62 and 63, the passage 63 beine of greater diameter than the passage 62. The inner end of the passage 62 is intersected by radial ports 69, and the inner end of the passage 63' yby radial ports 10. A check valve member 64 held against the shoulder intermediate the bores 62 and 53 by a spring 65 permits the flow of oil from passage V 62 into passage 63 but prevents return flow. Internal passages 64a in the valve member 6'4 provide an outlet for the chamber 63 to prevent trapping of fluid behind the check valve. The outer end of the compression spring 65 Yisy guided by a plug 65 slipped into the borev S3 and held in place byja fitting IiI screwed into the tapped outer endl of the bore and sealed by an O-ring (58 or an equivalent sealing ring. The fitting 61 serves asa plunger stop and in addition is formed with a transverse bore 68a for connection of a manual control lever to the plunger. The setting of the valve plunger to its correct positions and its retention therein are facilitated by a detent assembly II screwed into a tapped hole in the right hand end of the plunger ZI and mounting plungers I2 urged outwardly by a spring 12a into engagement in circumferential grooves 25a in the housing 25. y

The inlet opening 8 in the upper portion of the valve communicates with the chamber 44 having two branches 44u and 44D terminating in enlargements-ofthe bore 23. A bore 28 through the casing parallel to the bore 23 and intersecting the chamber 44 provides for the mounting of two automatic valves which form part of the system, a now control Valve and a relief valve. The seat for the relief valve is formed by a bushing 29 retained in the bore 28 by a set screw SI. The relief valve assembly comprises a hollow plunger 'I4 normally held against its seat in the bushing 2S by a compression spring 38. The spring is retained by a hollow threaded cap 3'7 in which is threaded the spring tension adjustment screw it the inner end of which abuts the spring guide 39. A lock nut 4I and cap nut 42 lock the adjusting screw andA cover its exposed end. A gasket 43 is compressedv under the flange of the cap 31. Whenever the pressure in the chamber t into which the pump discharges becomes excessive, the plunger 'I4 is forced to the right against the tension of the spring 38 and oll escapes through the central bore 14a and radial passages 144D of the plunger into the chamber 45h which discharges into the tank through the port I4. The operating pressure of the relief valve may be set in the obvious manner by adjusting the screw llll).

The flow control valve assembly which is mounted in the left end of the bore 28 is provided to control the flow of oil from the cylinder to the tank. This valve prevents return flow unless there is positive pressure in the chamber 44 and regulates the return ow to secure smooth action of the cylinder I5 and prevent drawing a vacuum in the cylinder. The valve comprises the ow control plunger 32 slidable in the bore 2B to regulate flow of oil from the chamber 5i! which communicates with the valve operating plunger2l to the chamber 5I from which the oil discharges into the reservoir through the outlet I3. The flow control valve plunger 32 is in the form of a hollow cup, a blind bore 'i8 therein being closed lby a screwed-in plug 15. This plunger is formed with a thin wall and is relatively` light in weight. The radial inlet passage 'I6 in the plunger 3 2 is always open to the chamber 58. Radial passages as indicated by 11a, 11b,-

and Tlc permit flow of oil from the .interior or the plunger 32 to the chamber 5I when Ithe plunger moves to the left from the position shown in Fig. 1. The ports 11 areV staggered longitudinally of the plunger and Iare graduated in size. The passage 11e :also serves i to admit oil into the chamber 18 in the plunger32except inthe case of extreme movement of the plunger to the left, in which case -oil'ffiows through the opening 13 whichI is unobstructed.` The plunger 32 is urged to the left to openthe ports 11`by the action of a pin 15 sliding in a bushing 3ll i`1tted in the bore 28 and locked in position by a setscrew 3i. chamber 44 and is thus urged tothe left bythe pressure of the fluid in the pump discharge line. The head 15a. of the pin bears against the :inner end of the plunger 32. The plunger is urged to-V Ward its closed position by a compression spring Si engaging a Washer 80a for which a snap' ring 3G received in a groove in the `plunger.'serves'yas an abutment. Thezspring 8iVv isv retained against a shoulder 33a of a `dashpot casingmemberf'33 screwed into the tapped-out end of fthe; bore .23. The dashpot casing 33 is formed with a1 hexagonal head under which the gasketi.v is come pressed. v f

The casing 33 orms apart of a dashpotuassembly described and claimed in my. copending application'Serial No.'152,689, filed `June 5; 1947. In addition to the casing 33 the dashpot'comprises a sleeve 34 closely'tting therein'and urged outwardly of the casing bya compression spring 35. The face of the plunger 3 5 'which normally bears against the cap'l ofathe valveplunger 32 is-formed with a radial groove 82 which iormsa restricted passage for the escapeofl cil-.fromithe internal chamber ofthe dashpot.

The dashpot is provided to stabilize the action of the plunger 32 and thus that of the power cylinder i5. The action of the dashpot is as follows: When the valve plunger 32 moves to the left to open the ports 11, movement can only take place by moving the dashpot sleeve 34- to the left, thus contracting the chamber S3 and forcing oil out through the small groove 82. If the pressure in the chamber 44 decreases, the spring 8| can close the ports 11 rapidly, the plunger simply moving away from thedashpot sleeve. When this occurs, oil can flow into the dashpot over theentire face, and the chamber S3 will fill rapidly, the sleeve 34 thus closely fol-` lowing the plunger 32 under the action of' the spring 35. Rapid reversals yof the plunger are thus prevented, since there can never be any substantial free travel of the plunger 32v to theleft.

The entire face of the iow control valve plunger could be exposed to pressure in the inlet line. In the preferred construction shown herein only the relatively small area of the pini 15 is so exposed and thus lighter hydraulic thrust is exerted on the plunger. This feature makespossible the use of a relatively light plunger return spring 8i. K

A bleeder passage K4 through the valve casing and thev bottom of the tank 5 prevents fluid blocking of movement of the plunger 32 and dis' charges any seepage past the pin 15. j In some cases the passage 54 may advantageously be made small enough to act as a restricted oriiice and thus slightly retard movement of the plunger 32`to the right. f i

A passage 53 drains oi into the'chamber 5| oil `which may seep past the left end of the control plunger 2| and a passage 52 discharges fluid The body'of the pin 15 projects into the escaping around the right endet vthe plunger into1-thelreturn`chamber 45h. A'V collar" 13 retained beneath the-datent housingj25`servesas a stop to limit leftward movement of ythe operatingplungerli.-

As previously stated,.the oilcirculated by the pumpV is diverted in the fhold position of the valve into the chamber 45a. and oil escaping past the relief valve 14V is dischargedintofthe chamber 45h which communicatesdirectly with the tank. The chambers Maand' 45lrare normally in com-y munication through vaport 41. An'auxiliary .port 46 opening from the chamber 45a to the outside of the valve assemblyv ist; normally closed by a Y plug. With" this arrangement vthe chambers 45a and`45b becomein effect one chamberA opening directly into-:thetankvInflthe event,` however, that itr is udesired to "operatev:more than one mechanismy from the punip-the-pcrt 41 maybe closed by a plugan'd lthe'port45'may be opened and Y connected by' a-conduit 'toafsecond valve orr the like. With the' valve`ir'1the'hold position l of Fig. 1`, the oil fromtherpump thencirculates through the chamber 44, around'the' relieved porv tion 6| of the valve operating vplunger 2l, through the-chamber @5u and port 46 to" the v"second controlmeans (notlshown). Y

Although the valve is shown herein in a form adapted formountng directly onithe bottom of the oil reservoinit willbe obvious to those skilled in the art thatthev valve may Vbe very simply modified =for -installation vapart'-ffrornthe tank.

One convenientWay-of accomplishing lthis is 'to provide a cover for the valve fittingove'r the top thereof and 1in which a manifold is 4formed com- Having now disclose-df in detaill thepreferred structure of the valve,y the operation of the sys-z tem may best be understcodby reference t0 Figs.

2 to 5 in which thefstructure of the valve is shown somewhat schematically and thefour operating conditions ci the systemkare shown.

.In Fig, 2, and in 'Fig'. lglthe valve operating plunger 2l jis in the fhold` position in which the piston p I 6 isy 4hydraulically locked against movement in either direction.v` The chambers .48 and 49 which areconnected to the ends of the cylinder are closed by the operating plunger 2|, chamber 48- being closed by the lands 5.5 and 56 and the chamber 49 Aby the lands 56 and 51. The pump discharge into the'chamber 44 flows through the branch "44bgaround the groove El of the plunger into the return passages 45 and to the tank. The ports" 69 of theV operating plunger are blanked, `v being intermediate the passages 44a and 44h. ,'There is thus no 'ow through the passage r62 ofthe plunger 2|, and the flow controlvalve 32 is inactive. VSince the pump output. is discharged freely,v there Will be substantially no pressure'infthev chamber. and the valve 32 will be in closedpositionI under the action of the springjl; l

If itis desired to raise thefbladautheplunger 2| is moved to its extremeleftposition as shown in Fig. 3. In this ,positionchamber 44h is closed by lands51 and 58 of' the plunger'butA radial ports f 69 A,are lalignedwith'chamber 44a, permitting the oil delivered by the pump to flow through the internal chamber 62 ofthe plunger, lift the check valve 64, and flow out through ports 10 which 7. are aligned with'the chamber 4 3.- Fromfchamf ber 48 the oil iiows through portl I finto the left hand end of cylinder I5, :driving/the piston ,to the right. Returnv flow fromtheright hand end of the cylinder enters the valve through port I2, and from passage 49 -iiows aroundundercut' of the plunger into passage 50. .Since the cylinder I5 is doing work, a positive pressurewill be maintained in the chamber 44k and thelpin 'I5 will move the ow control valve-'32 to its extreme left position, thus allowing unrestricted return flow. The chamber 50 is thusI opened to the return port I3 through port 16, `the chamber of the plunger 32 andports 11. If, howevenfor any reason the normal'load isreversed and the piston I6 is urged to the right vby the mechanism to which it is coupledso. thatthe clearance volume'in the left handn end; of cylinder- I5 tends to increase more rapidlyfthan it can be lled. by the pump discharge, the pressure-fin thechamber 44 will immediately' dropand vthe spring, BI

- will move the iiowcontrol valve to the right to restrict the outlet from;the cylinder suiciently to maintaina positive pressure in thev chamber 44 and the left hand end of the cylinder; The I positive pressure inthe inflow lineand prevent drawing of avacuum in the cylinder. A

With the valve set to the lower position-illustrated in Fig; 4 the overall operation is veryjsimilar to that of the raise position.` Chamber 45a is cut oi fromchamber 44h by the land 5'! of the valve. Oil from the-pumpi'lows into chamber 44 and from branch 44h through the ports 69, passage 62, and ports- 10. into lthe chamber 49 from which it isV discharged through port I2 to the right end of the cylinder I5. Discharge from the cylinder enters the valve through port II and proceeds from chamber 48 around the undercut59 into the chamber50 and thence to the tank throughthe ow'controlvalve as previously described. Theoperation of Vth'eiiovv control valve in the lower positionis identical with that in the raise position.` Normally, during lowering, the cylinder is urged by' 'the load, and the valve 32 automatically restricts the return ow to equal vtherate of supply from the pump. If, however. the'cylinder is doing work, as for instance, pushingaib'ulldozer blade' into theground, the increasfejof pressure in the'ch'ame ber 44 opens, the flow control valvefully, mini- V mizing restriction in theQreturn' line from the cylinder. 'A Thus in both thefraise? and`flower positions uid is delivered yfrom, the pumpn into one or the other end of Vthe cylinderto movethe load positively if force is required tomve it; 1and the return flow from the cylinder is .automatically throttled to prevent the ,'pistonj from running away from the pump ii the load, should be, drive ing the piston positively. Theopening of the now control valve is retardedQbythe dashpot, preventing too,l great 4openirtg, with resulting oscillation cf the valve and jerky 'actionE of the cylinder. If, however,.. the load'` or pump, speed changes, the iiow control valve can closerapidly, responding immediately t ov 'the changed conditions. Thus smooth actionis secured in both directions, regardless of,whether fthe load isjpositive or negative,y .andi regardless vof fluctuations in theload orinth'ef rate, of', delivery from the pump. Y' In the float positi n ..theivaiveiiustratu in Fig. 5 the two ends of the cylinder are interconnected to permit free movement of the piston in either direction. Undercut 59 bridges chambers 48, 50, and '49 and undercut 60 interconnects chambers 44a. 'and 49. Thus the pump, both ends .of the cylinder, and the chamber 50 are in constant communication with each other. The piston is free to move in either direction and increases or decreases in the volume of the cylinder from the displacement of the piston rod are compensated for by ow of fluid from the pump or to the tank` It will be noted that the return passage 45a is closed by the land 51, and iiow of oil to the tank in the float position is through the flow 'control valve 32. A positive pressure is maintained in the manner previously described, that is, valve 32 automatically throttles the return iiow suiciently tomaintain the desired pressure in chamber 44, which pressure is conducted to both sides of the piston. Valve 32 is illustrated as open, but it may Vclose if the entire pump discharge is being used to make up for the difference in volume of the two ends of the motor. If, for example, the piston i6 floats to the right, a greater volume of fluid will be required to fill the left end of the cylinder than is displaced from the right end because of the displacement of the piston rod at the right. Because of the positive pressure maintained. in the system, the additional oil will be supplied from the pump and any tendency to draw a vacuum in the cylinder is prevented. In the event'that the piston floats to the left, some fluid will be displaced from the cylinder'and the ilow .control valve readily adjusts itself to handle this `flow in addition to the pump displacement.

The prevention of voids in the cylinder or valve is highly benecial to the operation of the system, insuring that the operating cylinder will always be immediately responsive to operation of the operating control plunger 2I. With every part of the system always full of oil there is immediate response when the control is moved to any position since there can be no lag while a void is being lled by the pump. In the normal operation of the system, the relief valve 'I4 remains closed. If, however, with the valve in the raise or lower position the :piston reaches the end of its stroke or encounters a resistance greater than the system is designed toro-vercome, pressure will immediately build up in the chamber 44, lift the relief valve 74, and bypass the' pump dschargeinto the chamber 45h (Fig. l) and out through port I4.

Check valve 64 prevents backflow from either side of the hoist during the shifting of the plunger 2|l from one operating position to another. It prevents reversal of flow from the cylinder in the event vof a power failure or a break in the supply circuit when the valve is in the raise or lower position, and it also prevents flow from Chamber 49 to chamber 45a when plunger 2| is in the float position.

y The division of the passage through which return flow of oil takes place in the hold position into the two parts 45a and 4513A connected by the threaded port 41 adds another valuable feature to the valve. With previously known valves it was practically impossible tooperate a second control means in tandem with a rst, especially when the rst valve was mounted directly on the bottom of the supply tank. With the improved valve, such tandem operation is feasible without vacca-824 interfering with the vop'eratlonoi vthe iirstor basic valve. .1 a

vThe description so far hasbeenl restricted to the-single operation. In .such installations .port 41. is left vopen andzan auxiliary return port 46 in thechamberlla (Figi) is plugged. Fortandem operation the port 41 is closed by a plug and vport eSis connected to` thesecond valve. With this organization the passage 45h ,functions as a bypass to the tankonly when the relief valve V'M is opened .by excesspressure.; -In the hold position4 the. pump discharge .isffed Afrom port 8 through `chambers M and 4411,; undercut ,61, chamberV .45al and portjlS-.to the V,second valve where it mayibe utilized in any desired manner. The second .valve .is supplied onlywhen the rst is jin 'fhold ..Thismay be. desirable ,inY many cases,A and, moreover, this conditionis-not materiallydiierent from thatwhich, exists in the case of .a conventional multi-plunger control valve whereinonlyone operating plunger is used at any one time. With lthis arrangement of thereturn passage 45a, 45h it is possi'ble. to use the same source of fluidsupply to operate more than one set of mechanisms ifdesired and lthuseliminate theneed for a secondsupply'source. Y Y *The-,hydraulic power-t systemV-gdescribed herein as the preferred embodiment ofmy viIlVenti'on employs a double-acting ram which-may .beloonnected to a bulldozer blade or other device to be moved. The double-acting. cylinder or ram is but one species of a class of reversible hydraulic motors, the. direction of operation of which is determined by interchanging inlet and discharge connections, and thus controlling vthe direction of flow of fluid through the motor.v This is oommonly called port-reversing. Some motors of this class' are capable of unlimited operation in either direction and are thus superiorto a ram for certain types of installation.v In some portreversing motors, uid actually llows through the motor. In ram-s, flow into one end and out of the other end is analogous, although there is no actual ilow through the motor. It will be apparent that the principles of this invention and the preferred form of valve yembodying those principles disclosed herein inay be employed with any motor .of the port-reversing type.

The terms raise and lower as applied to the valve positions, while appropriate to certain installations, are arbitrary. These positions might equally well be denominated right and left,

, interconnected for free movement of the motor.

in and o-ut, or forward. and reversa the last named being perhaps' the-most general identiiication of these positions.. f .l

In the appended claims, reference to a motor is to be understood as applicable to hydraulic imo.- tors generally, and not as specic to cylinders or rams. The term pump is chosen merely for convenience 'andis intended to denominate any source of fluid under pressure for the operation of the motor. A'l'he'term reservoir means any receiver for fluid under low .pressure after einployment in the motor.

vIn the claims,rreference to valve positions by the terms forward,"v reversa hold and iloatj have the following meaning: forward means a position in which fluid is delivered from thev pump to a first inlet of the motora'n'd permitted to escape from the second inlet; reverse nIn the jcas'e: of. aA` motor-V in which fluid flows Ithrough the motor', as distinguished from a ram, forwardmeans a position 'ijn which iluid is .circulated through .thel `motor -infonze direction by the pump; reverseis the valve position in whichfluid is circulated :through the-motor in' the opposite direction lby the pump; fhol'd is, the position in which circulation ofluid through the motor Vis prevented; and float lis the position in which fiuidis free to circulate through themotor in either direction. j

The term. Operating positioni of., the valve means any positiongcausiilg 0r permitting l,movement .of the lmoto-r such -asthe forwardi revers-eff and iloat .positions asdened or equivalents.-r 'f y Although the .foregoing description 'isn necessarily of a detailed character, in order` that the invention may be-completely set forth,- it is to be understood that the specific terminology isnot intended to -be restrictive or confining, and that various rearrangements .of parts and modifications of detail may be yresorteclto without departing `from the scope or ,spirit of the VKinvr'entijon .was

herein claimed.A

l. A hydraulic control` devicecomprising a casing having an inlet port, two outlet ports-a return Dort. and two discharge chambersrformed therein; a flow 4control valve interposed ,between one discharge chamber and ther,etiirn port; and a settable y distributing lvalveformedito :selectively interconnectv the several ports; and thevgdischarge chambers as follows; to connect-the `inletport selectively-to either, outletporter both' joutlet ports;; to connect either Outletportr to 'the disi charge rchamber.when the other outlet port is connected to' theinletport, and connect both out= let ports to saidone discharge Ychamber whenthe inl-jet port is connected to both outlety ports and` to. simultaneously isolate the other discharge charn: ber;',.Ineansresponsive topressure in the inlet port to open-'the flow control valve; damping means operative to retard opening movement of said valve 4during discharge ow of liquid past .the same; and lbiasingf'` means tending to close said Valve.v l 1v v 2`. A control .device adapted tocontr'oll the cp-l eration of `a; ,reversibl'e'm'otor-i'n a s stein-iii'cliid ing. the motor, a pump, and a reservoir.v thesai'd device comprisingla casing formed with an-inlet chamber adapted to" be connectedl'tothe rtir-np,A

first and secondv outlet 'chambers `adapted te. bei

connected to the inlets of the motor, bypass means a position in whichv iluid from the pump either inlet of the motor isprevented; fioat voir, and a return"Lehramber; anew controllvalve interposed betweerrtl'iev .return` chamber andthe reservoir; and a distributing valve settablete three position'sffa first'ric'isi'tionl in which t'l'ielo'iit let chamberslare. isolated 'and the inlet -and bypass chambers are' connected, a second positie n in vwhicl'i.' the inlet` and rst outlet chambers are connectedv and: tnesecord outletv and return cnamers are'` 'connectedane' thi-r" in w .ien the ijn-ietseccndroutiet feta. ersand-first outlet andi-return clfiar'nbers are con'-A nected; means responsive topressure in theinlet chamber to open theiflo'w control v'ajl'veydamping" means operative to retard openingmcvement said valve' during discharge new' of iiouiej'past. the' same; and 'biasing means tending. to closev said .valve andc'haracteri'zed" by `'a "closing" 'force which increases in direct relation to valve opening. Y

3. VA control device adapted to control the operation of a reversible motor in a system including the motor, a pump, and a reservoir: the said device comprising a casing formed with an inlet chamber adapted to be connected to the pump, iirst and second outlet chambers adapted to be connected to the inlets of the motor, a bypass chamber adapted to be connected to the reservoir, and a return chamber; a iiow control valve interposed between the return chamber and the reservoir; and a distributing valve settable to four positions, a iirst position in which the outlet chambers areisolated and the inlet and bypass chambers are connected, a second position in which the inlet and iirst outlet chambers are connected and thesecond outlet and return chambers are connected, a third position in which the inlet and second outlet chambers are connected and the rst outlet and return chambers are connected, and a fourth position in which the inlet, outlet, and return chambers are connected and the by-pass chamber isolated from the inlet chamber; means responsive to pressure in the inlet chamber to open the iiow control valve; damping means adapted to retard opening movement of the flow control valve; and spring means operative to bias the iiow control Valve to closed position.

4L A control device adapted to control the operation of a reversible motor in a system including the motorfa pump, and a reservoir: the said device comprising a casing formed with an inlet chamber adapted to be connected to the pump, rst and Vsecond outlet chambers adapted to be connected to the inlets of the motor, a bypass chamber adapted to be connected to the reservoir, and a return chamber; a iiow control valve interposed between the return chamber and the reservoir; and a distributing valve settable to four positions, a iirst position in which the outlet chambers are isolated and the inlet and bypass chambers are connected, a second position in which'the' inlet and rst outlet chambers are connected and the second outlet and return chambers are connected,.a third position in which the inlet and second outlet chambers are connected and the rst outlet and return chambers are. connected, and a fourth position in which the inlet, outlet, and return chambers are connected and the by-pass chamber isolated from the inlet chamber; means responsive to pressure in the inlet chamber to open the iiow control valve; and means operative to close the flow control valve.

5. In a hydraulic control device, a body formed with an inlet chamber, a return chamber, and a discharge chamber intermediate the inlet and return chambers, and formed with a bore interconnecting the said chambers; a hollow piston closed at the ends so as to be balanced against 'fluid within the piston and formed with lateral openings into the void therein, and reciprocable in the said bore; the pistonbeing slidable from a closed position in which the openings are Without the return chamber to an open position in which at least one opening registers with the return chamber, at least one opening always registering with the discharge chamber; the hydrostatic effeet of fluid in the inlet chamber urging the plston toward open position; means operative to urge the piston toward closed position; and a unidirectional damping device operative to retard movement of the piston toward open position during flow of discharge liquidV through said one opening of said piston.

6. In a hydraulic control device',`a'body formed with an inlet chamber, a return chamber, and a discharge chamber intermediate` the inlet and return chambers, andforined with a bore interconnecting the said return and dischargechambers; a hollow piston closed at the ends by means iixed to said piston, said piston being formed with lateral openings into the void therein, and reciprocable in the said bore; a passage between the inlet and discharge chambers; a, plunger of less diameter than the piston slidable in the 'passage and engaging the piston; thepiston being slidable from a closed.' position Yin which the openings are withoutv the return chamber to an open position in which at least one opening registers with the return chamber, at least one opening always registering with the discharge chamber; the plunger vurging the piston toward open position under the hydrostatidefiect of fluid in the inlet chamber; means operative to bias the piston toward closed position; and a unidirectional damping device operative to retard movement of the piston toward its fully open position after said piston has reached a position wherein one opening therein communicates with said return chamber. f

'7. A hydraulic control device' comprising a casing having an inlet port, two outlet ports, a return port. and two'discharge chambers formed therein; a iiow control'valve 'interposed between one discharge chamber and the return port; and a settable distributing valve formed to selectively interconnect the several ports and the discharge chambers as follows: to connect the inlet port selectively to either outlet port or both outlet ports; to connect either outlet port to the discharge chamber when the other outlet port is connected to the inlet port, and connect both outlet ports to said 'one discharge Vchamber when the inlet port is connected to both outlet ports and to simultaneously isolate the other discharge chamber; means responsive to pressure in the inlet port to open the flow control valve, damping means operative to retard opening of the iiow control valve during iiow'of discharge liquid past the flow control valve, and bias means tending to close the flow control valve, said valve being indifferent to the pressure of exhaust liquid.

8. A hydraulic control device comprising a casing formed with an inlet chamber, an outlet chamber, first and second motor chambers, a by-pass chamber and-a return-chamber; a flow control valve interposed between the return chamber and the outlet chamber; and a distributing valve settableto four positions, a first position in which'the motor chambers are isolated and the inlet and -by-pass chambers are connected; a second positionv in which' the bypass chamber is isolated, thev inlet and iirst motor chambers are connectedl andthe second motor and return chambers are connected; a third position in which the by-pass chamber is isolated, the inlet and second motor chambers are connected and the iirst-motor and `return chambers are connected; and a fourth position in which the by-pass chamber is isolated and the inlet, return and both motor chambers are simultaneously connected; means responsive to' pressure in the inlet chamber to open the iiow control valve; damping means to retard opening movement of the last named valve during flow Yof liquid past said valve; and-means operative to .connection to a reversible motor, a sett'able Q 'distributing valve in said casing formed toselectively establish communicationV between the inlet passage and one of said outlet ports andv the return passage and the other of said outlet'ports, a throttle valve in said return passage, means responsive to pressure in said inlet passagev for opening said throttle valve, a'spring for closing said throttle valve,` pistoniandcylinder elements defining a liquid chamber, one of said elements being Xed in the casing and the other movable and spring extended into said return passage to engage the end of said throttle valve, and a port in said movable element leading into said chamber that is partially closed when the element engages said throttle valve to provide a restricted damping orice.

10. In a hydraulic control device, a body formed with an inlet chamber, a return chamber, and a discharge chamber intermediate the inlet and return chambers, and formed with a bore interconnecting the said chambers; a piston reciprocable in said bore and formed with passage means to establish communication between said discharge and return chambers, said piston being balanced against the eiiects of fluid pressure within said discharge chamber, said piston being slidable from a closed position in which said passage means are entirely. within the discharge chamber thereby blocking communication between the discharge and return chambers, to an open position in which at least a portion of said passage means is within the return chamber, at least a portion of said passage means being always within the discharge chamber; said piston having a portion exposed to the hydrostatic eiect of fluid in the inlet chamber for urging the piston toward open position; and a unidirectional damping device operative to retard movement of the piston toward open position during flow of discharge liquid through said passage means.

11. In a hydraulic control device, a body formed with an inlet chamber, a return chamber, and a discharge chamber intermediate the inlet and return chambers, and formed with a bore interconnecting the said chambers; a piston reciprocable in said bore and formed with passage means to establish communication between said discharge and return chambers, said piston being balanced against the effects of fluid pressure within said discharge chamber, said piston being slidable from a closed position in which said passage means are entirely within the discharge chamber thereby blocking communication between the discharge and return chambers, to an open position in which at least a portion of said passage means is within the return chamber, at least a portion of said passage means being always within the discharge chamber; said piston having a portion exposed to the hydrostatic eiect of fluid in the inlet chamber for. urging the piston toward open position; means to bias the piston toward closed position; and a damping device to retard movement of the piston toward its fully open position after said piston has reached a position wherein said passageway establishes communication between said discharge and return chambers.

12. For use in a hydraulic system including a motor; reversible by .interchanging two portsv as between :inletgand f discharge, a reservoir for liquid,y ,and -a continuously: operating.. pump fed with,liquid.;andservingx to-deliver liquid under pressure, a@ control `valve vmechanism comprising in combination,- av flow control` valve balanced so asto be indifferentfto,thepressure of liquid whose flow it vcontrols,.saidvalve having a discharge for connection; with the reservoir and an inlet; biasing means continuously effective to urge said valve toward its closed position; pressure-responsive means, subject to the pressure of pump delivery, for urging said valve in its opening direction; one-way damping vmeans continuously effective to retard opening movement of said flow control valve; and a maneuvering valve having connections, one for each motor port, a reservoir connection' and a connection for the pump delivery, said valve having at least three functional positions, namely a hold position in which it closes both motor port connections and connects the pump delivery connection with the reservoir connection, and two relatively reverse motoroperating positions in which respectively it connects a selected one of said motor connections to pump delivery connection and the other to the inlet of said ow control valve.

13. For use in a hydraulic system including a motor reversible by interchanging two ports as between inlet and discharge, a reservoir for liquid, and a continuously operating pump fed with liquid and serving to deliver liquid under pressure, a control valve mechanism comprising in combination, a flow control valve balanced so as to be indifferent to the pressure of liquid whose ow it controls, said valve having a discharge for connection with the reservoir and an inlet; biasing means continuously effective to urge said valve toward its closed position; pressure-responsive means, subject to the pressure of pump delivery, for urging said valve in its opening direction; one-Way damping means continuously eiiective to retard opening movement of said flow control valve; and a maneuvering valve having connections, one for each motor port, a reservoir connection and a connection for the pump delivery, said valve having at least three functional positions, namely a hold position in which it closes both motor port connections and connects the pump delivery connection with the reservoir connection, and two relatively reverse motor-operating positions in which respectively it establishes a one-way flow path from the pump delivery connection to a selected motor connection and connects the other motor connection to the inlet of said flow control valve.

14. For use in a hydraulic system including a motor reversible by interchanging two ports as between inlet and discharge, a reservoir for liquid, and a continuously operating pump fed with liquid and serving to deliver liquid under pressure, a control valve mechanism comprising in combination, a flow control valve having a discharge for connection with the reservoir and an inlet; means biasing said valve toward its closed position; pressure-responsive means, subject to the pressure of pump delivery, for urging said valve in its opening direction; one-way damping means serving to delay opening movement of said flow control valve; and a maneuvering valve having connections, one for each motor port, a reservoir connection anda connection for the pump delivery, said valve having at least four functional positions, namely a hold position in which it closes both motor port connections and connects the pump delivery connection with the reservoir connection, two relatively reverse motor-operating positions in which respectively it connects a selected one of said motor connections to the pump delivery connection and the other to the inlet of the flow control valve, and a float position in which it closes the reservoir connection, and connects the pump delivery connection and both motor port connections together and to the inlet of the flow control valve.

HALL KIRKHAM.

REFERENCES CITED The following references are of record in the le of this patent:

Number 15 Number 16 UNITED STATES PATENTS Name Date l McCauley Aug. 18, 1925 Temple Apr. 17, 1934 Monroe Aug. 14, 1934 Bufngton Sept. 17, 1940 Herman et al Sept. 7, 1943 I vers May 28, 1946 Gardiner July 9, 1946 Towler et al May 27, 1947 Lauck et al Dec. 2, 1947 Stephens Aug. 2, 1949 FOREIGN PATENTS Country Date Great Britain June 2, 1932 

